Mouryou no Hako is a Japanese novel written by Natsuhiko Kyougoku about a detective investigating the grisly murders of schoolgirls. In 2008, it was turned into an anime series by famed studio Madhouse.
What's interesting about this is that the character designs for the anime were done by CLAMP. As you'll see in the pics below, this is quite a departure in look from Code Geass, another anime with CLAMP designs.
Let it be said that those ladies are quite versatile.